Integrated land-use and agricultural emissions modeling reveals untapped mitigation potential in livestock feed substitution

CONTEXT With rising global demand for animal-sourced foods, controlling greenhouse gas (GHG) emissions from livestock production has become critical to mitigating climate change. While prior research has quantified the global potential of using agricultural by-products to replace crop feeds, a comprehensive evaluation of the associated GHG mitigation benefits—particularly when considering both land-use change (LUC) and agricultural production emissions—has not been addressed. OBJECTIVE This study aims to evaluate the global integrated GHG mitigation potential of replacing livestock crop feeds with agricultural by-products, by combining emissions from both land-use change and agricultural activities, while also identifying regional variations in this potential. METHODS Five major agricultural by-products (cereal bran, molasses, sugar beet pulp, citrus pulp, and distillers' grains) were selected to replace six energy-intensive crop feeds across 19 global regions. The methodology comprised four key steps: (1) developing region-specific substitution matrices based on previous literature; (2) estimating land-use change emissions of replaced crop feeds and replacing by-products using spatially explicit data; (3) assessing agricultural emissions of replaced crop feeds and replacing by-products with statistical data; and (4) calculating global GHG mitigation potential as the difference between emissions from replaced crop feeds and those from replacing by-products. RESULTS AND CONCLUSIONS Globally, replacing crop feeds with agricultural by-products was projected to reduce GHG emissions by 167 Mt. CO₂-eq. (80–276 Mt. CO₂-eq) annually over a 30-year timeframe, which accounts for 9 % (4 %–14 %) of the total annual emissions from crop feeds; 80 % of this reduction is attributed to land carbon restoration. Regionally, South-eastern Asia (31 Mt. CO₂-eq) and Southern Asia (30 Mt. CO₂-eq) emerge as mitigation hotspots, primarily due to their status as tropical and subtropical regions with high native land carbon stocks. Eastern Asia, Eastern Europe, Southern America, and Western Europe exhibit mitigation potentials ranging from 14 to 20 Mt. CO₂-eq, driven mainly by their large volumes of replaced crop feeds. SIGNIFICANCE This study advances the development of a framework for assessing land-use and agricultural emission reductions from crop feed substitution with by-products. It provides a foundational reference for further research on mitigation strategies in the global livestock feed sector.